The YCC Flow Cytometry Shared Resource was constituted in 2004 via a merger of the exclusive YCC flow core and an existing flow core that serviced some but not all users at the school of medicine. This merged core, an institutionally managed shared resource, was relatively new when the prior funding cycle commenced. The new Flow Cytometry Shared Resource has been very successful, and has grown fairly dramatically since the last review. Over the last four years we have added three new cell sorters, three new LSRII analyzers, and an Amnis Image stream X.Jn addition we have acquired, with help from YCC, four new Stratedigm digital analyzers with compact footprints. They will replace two legacy analyzers and thus we have a net increase of two further analyzers. We have opened two new sites and expanded to 4 rooms from two in our primary site. Our budget has also increased by -50% and our personnel have increased from four to seven, with an eighth employee currently being recruited. This growth has been driven by the strength of immunology research, strong recruitment in the Cancer Immunology area, expansion of Human and Translational Immunology, and importantly increased accessibility and usefulness of the Flow Cytometry Shared Resource to nonimmunology cancer-related research. Specific Services Analysis is generally carried out by users after they have been trained to do so (see below/). This is relatively straightforward, and we currently have over 400 registered, trained individual users. Having users operate the analyzers has allowed us to dramatically lower the costs per hour to the YCC Pis compared to the previous system. However, for an added fee, the facility will carry out analysis for users who do not wish to do so themselves. In contrast. Cell Sorting is generally carried out by a trained operator on one of the three machines described above. The machine/operator is selected by the user based on capabilities and availability. The FACSAria can be operated by a highly trained user who has completed a special training session and has been certified. This facilitates extra long sorts or after hours use. In addition to analysis and high speed cell sorting the FACS Facility provides users with an array of additional resources and services. The FACS Facility hosts a website, http://medicine.yale.edu/labmed/cellsorter, which contains a variety of materials to assist users in performing or developing an experiment. This site contains protocols for cell preparation for analysis and cell sorting along with other more specialized protocols, such as DNA Cell Cycle, Ca++ Flux, Intracellular Cytokine Staining, and BrdU staining. The FACS Facility website also provides links to other FACS related sites, forums, and discussion groups. An important service of the FACS Facility is the training of new users. Novice users are required to attend an Intro to Flow Cytometry class that covers the basic premise of flow cytometry, machine operation, software use, and troubleshooting. The FACS Facility also offers experienced users training on more advanced machines such as the LSRII and the FACSAria. These advanced training sessions help users become proficient in performing multi-color digital analysis using the LSRII and independent cell sorting using the FACSAria. The FACS Facility provides reference manuals for all new users who attend a training sessions. The FACS Facility staff is also available for consultation on experiment design, optimization, and feasibility. The FACS Facility staff will work with users to develop appropriate fluorochrome combinations, help users optimize sample and antibody concentrations, as well as exploring possibilities to increase cell yield and viability. The FACS Facility also offers users a state of- the-art data analysis center. This analysis center has both PC and Mac computers that allow users to analyze data on various platforms (FACS Diva, CellQuest, CellQuest Pro, ModFit, Flowjo, and WinMDI) free of charge. The FACS Facility sponsors product seminars, typically 4 to 6 per year. These seminars allow users to become familiar with products and to query representatives on specific aspects and applications of a product. The large number of facility users allows for the negotiation of substantial group discounts on supplies, reagents, and analysis software.